1. Field of the Invention
The present invention relates to a packet data network and packet data transfer method, and more particularly to an asynchronous transfer mode (ATM) packet network which is suitable to a radio communication network, and a method for transferring packet data in the same.
2. Background of the Related Art
Research is now in progress for introducing ATM switches into cellular/personal communication service (PCS) mobile communication systems which are now commercially available. One proposed example is a mobile communication network utilizing an ATM switch for transferring data from a cellular mobile terminal to a receiver, which is shown in block form in FIG. 1.
In FIG. 1, user packet data sent from a mobile terminal 11 is delivered to a radio network controller (RNC) 31 through an associated base station 21. Then, the radio network controller 31 transfers the delivered user packet data to a destination radio network controller or a destination packet data node (PDN) along a path determined by a mobile switching center (MSC) 41.
In order to select and determine a data path for the mobile terminal 11, the signaling between the radio network controller 31 and mobile switching center 41 and the signaling between the mobile switching center 41 and packet data node 61 are performed through signaling ATM adaptation layers (SAALs) which are provided respectively in the radio network controller 31, mobile switching center 41 and packet data node 61, as shown in FIG. 2, in the case where an ATM switch is used. At this time, one virtual circuit is assigned to each mobile terminal call to transfer user data.
However, when the radio network controller 31 and packet data node 61 serve as nodes of the communication network using the ATM switch, outgoing data from the radio network controller or packet data node must be transferred through a virtual circuit in a circuit switched manner based on the ATM switch, as shown in FIG. 3. For this reason, the radio network controller or packet data node has to assign such a virtual circuit under the condition that the associated mobile terminal establishes a data or speech call connection. There is a limitation in establishing a virtual circuit for the ATM switch with respect to every unit physical connection port, and a signaling processing time is further required for the virtual circuit establishment.
In other words, when a source mobile terminal establishes a packet path to a destination mobile terminal or an Internet host to receive a packet data service, the associated radio network controller, ATM switch, and packet data node interact to assign a virtual circuit to the established packet path. The assigned virtual circuit is kept in an active state while user packet data is transferred. It then enters a dormant state if it is not in use for a given period of time.
Thereafter, if the virtual circuit is reused within a prescribed period of time, it again becomes active. The virtual circuit, however, is released unless it is reused within that prescribed period of time. Consequently, if a large number of mobile terminals keep their paths in the dormant state at a time or region having heavy traffic, the number of virtual circuits for the packet data service may be insufficient as compared with the number of users.
In order to prevent the above virtual circuit insufficiency, dormant virtual circuits may be released unless data is transferred for a prescribed period of time. When released, the associated mobile terminal has to reestablish the released packet data path to resume the packet transfer, resulting in an inconvenience.
As a result, the conventional mobile communication network as shown in FIG. 1 is limited in the number of virtual circuits to be assigned as the volume of traffic increases above a threshold value. This makes it difficult to efficiently execute packet data communication.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.
An object of the present invention is to provide an ATM network that substantially obviates at least the above problems caused by disadvantages of the related art.
Another object of the present invention is to provide an ATM packet network in which, when an ATM switch is used to transfer radio packet data from a mobile terminal, such as a cellular device, terminating at a radio network controller to a wire packet network access node or another radio network controller or vice versa, one virtual circuit is established between the packet network access node and radio network controller and a method for transferring packet data in the same.
Another object of the present invention is to provide an ATM packet network in which packet data or packet sessions from a plurality of mobile terminals are multiplexed/demultiplexed and transferred on an established virtual circuit between a packet network access node and a radio network controller, and a method for transferring packet data in the same.
To achieve at least the above objects in whole or in parts, there is provided a cellular asynchronous transfer mode packet network comprising a plurality of radio network controllers, each of the radio network controllers for performing a channel assignment function based on a service option of a source mobile station to separate packet data and circuit data service paths from each other upon interfacing with a core network; a packet call controller connected in common to the radio network controllers in its radio service area for supporting a speech communication exchange function and location registration and mobility of the source mobile station and managing location information of the source mobile station and information of packet connection nodes; a mobile packet router connected in common to the radio network controllers for routing packet data or packet sessions from the radio network controllers to established transfer paths, respectively; and a plurality of packet data nodes connected in common to the mobile packet router, each of the packet data nodes routing a corresponding one of the packet data or packet sessions routed by the mobile packet router according to a destination identifier; whereby a virtual circuit is established between a serving one of the radio network controllers and a target one of the radio network controllers or between the serving radio network controller and a target one of the packet data nodes and data blocks of the packet data or packet sessions are multiplexed/demultiplexed over the virtual circuit and transferred respectively to corresponding destinations via the mobile packet router, the packet connection nodes being the serving radio network controller and the target radio network controller or the target packet data node.
In accordance with another embodiment of the present invention, there is provided a method for transferring packet data in a cellular asynchronous transfer mode packet network which has one or more radio network controllers, a packet call controller, one or more packet data nodes and a mobile packet router, comprising the first step of establishing a virtual circuit between a serving one of the radio network controllers and a target one of the radio network controllers or between the serving radio network controller and a target one of the packet data nodes; the second step of establishing individual packet paths between the serving radio network controller and the target radio network controller or between the serving radio network controller and the target packet data node through the mobile packet router; the third step of multiplexing/demultiplexing individual data blocks of the packet data or packet sessions over the virtual circuit on the basis of a service specific convergence sub-layer protocol; and the fourth step of routing the multiplexed/demultiplexed data blocks according to authenticated destination identifiers.
In a preferred embodiment of the present invention, there is no need to assign virtual circuits respectively to packet paths for packet calls or packet sessions from individual mobile terminals. One virtual circuit is established between every radio network controller at which packet data from an associated mobile terminal terminates and another radio network controller or between every radio network controller and every packet data node. Further, a nearly unlimited number of packet paths is assigned over the established virtual circuit. That is, individual packet calls or packet sessions from the associated mobile terminals are multiplexed/demultiplexed on one virtual circuit interconnecting a serving radio network controller and a target radio network controller or interconnecting the serving radio network controller and a target packet data node. Moreover, it is not necessary to perform a signaling process to establish the respective packet paths of the mobile terminals.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.